JP2007010636A - Laser ranging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a calibration reference for simultaneously calibrating a distance and an angle in a laser ranging apparatus, orbitally calibrate a bias error in a scanner control changed under the space environmental condition, and improve the reliability. <P>SOLUTION: The distance and the angle are simultaneously calibrated by using an optical fiber 9 as an internal reference for calibrating the distance and considering an incident location of the optical fiber as a reference location for calibrating the angle. Since a beam entering into the optical fiber 9 is focused by a focus lens, and a pinhole is installed at a focus point and has a beam divergence angle or less, a resolution of the calibration accuracy is improved. Alternatively, a plurality of the calibration points are provided in a region in which the quantity of transmitted light is not changed by a scanner angle. An error in an actual displacement angle to an instruction angle to the scanner can be estimated by detecting and comparing a level of the received light. Its bias error is calibrated. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laser distance measuring device, and more particularly to a laser distance measuring device capable of realizing a calibration function.

  Although unmanned transport aircraft that transport goods to the space station are being developed in various countries, measurement technology related to unmanned docking at the space station has little track record and it is difficult to realize a sufficiently accurate measuring instrument in space. However, high precision and high reliability are particularly required for laser ranging technology mounted on transport aircraft.

  In addition, such a laser range finder must have an on-orbit calibration function, and it is important to have an original calibration standard inside and perform calibration whenever necessary.

  On the other hand, the demand for resources on transport equipment is severe, and large-scale devices due to limitations due to power and weight have problems in terms of mountability, and multifunctional and compact components are expected.

  In a two-dimensional scanning type pulse laser ranging device mounted on a transport station to a space station or the like, a bias error occurs in a ranging counter or angle detector due to changes in environmental conditions, and the target position measurement accuracy deteriorates. In particular, in the pulse laser range finder used on the ground, such errors can be calibrated by measuring an external reference target, but when using in space, a calibration reference should be prepared externally. There is a restriction that cannot be done.

  Further, a calibration reference for calibrating distance and angle using an internal reference is provided in such a laser distance measuring apparatus, and there has been no suitable means for accurately performing calibration with the internal reference.

  Accordingly, an object of the present invention is to solve the above problems, and a laser range finder capable of calibrating a bias error or the like that changes according to environmental conditions in an orbit to improve reliability. It is to provide.

  Another object of the present invention is to provide a laser distance measuring apparatus that realizes compactness by sharing an optical fiber for distance calibration for angle calibration.

  Another object of the present invention is to provide a laser distance measuring device provided with a calibration reference capable of simultaneously calibrating the distance and angle.

  Another object of the present invention is to provide a laser range finder having a highly accurate and reliable calibration function for rendezvous docking used when a transport aircraft is docked to an artificial satellite or space station.

  For example, a rendezvous docking laser ranging device used when a transport aircraft is docked to an artificial satellite or space station. The laser ranging device mounted on the transport aircraft side uses a satellite or space station marker (corner cube reflector). Etc.) is scanned with a two-dimensional scanner, the position of the marker is calculated from the distance information obtained from the round trip time of the pulse laser and the angle information of the scanner, and the distance measuring device that guides the transport aircraft changes according to environmental conditions It is characterized in that it has a calibration to correct the bias error of the distance and angle.

  In the present invention, an optical fiber is used as an internal reference for distance calibration, and an incident position on the optical fiber is set as a reference position for angle calibration, thereby simultaneously performing distance and angle calibration. At this time, the resolution of the calibration accuracy can be improved by converging the beam incident on the optical fiber by a condensing lens and installing a pinhole having a beam divergence angle or less at the condensing point. In addition, it is possible to estimate the error of the actual displacement angle with respect to the command angle to the scanner by providing multiple calibration points in the area where the transmitted light quantity does not change with the angle of the scanner and detecting the level of the received light. Calibrate the bias error.

  The laser distance measuring device of the present invention is a scanning type laser distance measuring device having a laser beam scanner, an optical fiber as an internal reference for distance calibration, and a reference for angle calibration within the scanning range of the scanner. An optical fiber having a position as an incident position is provided, and an optical fiber having the reference position for angle calibration as an incident position is shared with the optical fiber for distance calibration. The reference position for angle calibration is a position outside the scanning range of the target, and is defined by a pinhole of a shielding plate that is scanned with the laser beam.

  A condensing lens for the laser beam; and a shielding plate formed on the condensing surface of the condensing lens and formed with a plurality of pinholes having a beam divergence angle equal to or smaller than the angle. The pinhole is located in the scanning range of the scanner with little change in the amount of light in the scanning range of the scanner.

  Furthermore, the angle correction of the present invention is characterized in that if the absolute value of the angle measured by the light passing through a plurality of pinholes is shifted by the same amount, the angle bias is corrected and the bias error is calibrated. If the relative angle measured by the light passing through the pinhole does not match the angle command signal of the scanner, the gain of the angle command signal is corrected.

  The laser range finder according to the present invention is a laser range finder for rendezvous docking used when a transport aircraft is docked to an artificial satellite or space station. The marker is laser-scanned by a two-dimensional scanner, the position of the marker is calculated from the distance information obtained from the round trip time of the pulse laser and the angle information of the scanner, and data for guiding the transporter is output. To do.

  According to the present invention, an optical fiber for distance calibration as an internal reference and an optical fiber having an incident position as a reference position for angle calibration within the scanning range of the scanner are provided inside the laser distance measuring device. It is possible to realize a calibration standard capable of simultaneously calibrating the distance and the angle, and it is possible to improve the measurement accuracy.

  Further, since the incident position of the optical fiber as the internal reference for distance calibration is set as the reference position for angle calibration within the scanning range of the scanner, it is not necessary to install an individual optical fiber and it is possible to reduce the size.

  Further, by making the reference position for angle calibration outside the scanning range of the target, it becomes possible to acquire distance and angle calibration data simultaneously with normal distance measurement.

  In addition, it is possible to improve the resolution of the calibration accuracy by converging the beam incident on the optical fiber with a condensing lens and installing one or more pinholes with a beam divergence angle of less than the converging point at the condensing point. is there.

  Further, since the pinhole is located in the scanning range of the scanner where the change in the light amount within the scanning range of the scanner is small, it is possible to detect and compare the level of the received light, and the actual displacement with respect to the command angle to the scanner The angle error can be estimated, and the angle bias correction and the angle command signal gain correction can be performed.

  In addition, since the calibration function of the device alone can be realized, not only the reliability of the laser ranging device used in the space, orbital environment where the calibration standard cannot be installed outside is improved, but also the environment based on this calibration standard. It is possible to calibrate a bias error that changes depending on conditions on orbit.

(Description of configuration)
FIG. 1 is a diagram showing a configuration of an embodiment of a laser distance measuring device of the present invention. A configuration example of a laser distance measuring device having a distance / angle calibration function such as a distance and angle bias error is shown.

  The laser distance measuring device of the present embodiment includes a laser transmitter (laser) 1 that emits a pulse laser, a transmission / reception optical unit 2 that shapes a transmission beam and transmits received light to a light receiving unit, and two-dimensionally the laser beam. Scanner unit 3 for scanning, scanner driving unit 4 for outputting the angle command signal to drive the scanner of the scanner unit 3 and receiving the angle data of the scanner, calibration optical unit 8 installed at the angle reference position of the scanner unit 3, distance Calibration optical fiber (optical fiber) 9 having a predetermined length for calibration and transmitting a part of transmission light to the transmission / reception optical unit 2, transmission light from the laser 1, reception light from the optical fiber 9, and target (measurement) Light receiving unit 5 that detects received light from a corner cube reflector of a target, a marker, etc.) and converts it into a transmission / reception pulse of an electric signal, Ranging counter unit 6 that counts the distance and outputs distance count data, level detection unit 7 that detects the level of the received pulse, and scanner driving unit 4, and receives angle data from the scanner, and ranging counter unit 6 receives distance data, detects a peak level (peak point) from the level detector 7, and calculates a reference value from the calibration optical fiber and the calibration optical unit 8 from the distance data, angle data, and peak level. The control unit 10 calibrates the distance and angle by comparing the reference with the distance data and the angle data, and the power source unit 11 that supplies power to each unit.

FIG. 2 is a diagram illustrating a configuration example of the scanner and the calibration optical unit. The calibration optical unit 8 is provided corresponding to the transmission light side, and includes a transmission beam condensing lens 81 provided in the scanning range of the scanner and a light shielding plate 82 having a plurality of pinholes 83 provided on the focal plane thereof. And a calibration optical fiber 9 that takes in the transmission light transmitted through the pinhole 83 of the light shielding plate 82 from the incident end and transmits it to the transmission / reception optical unit 2. Here, the position of the pinhole 83 is formed so as to coincide with the reference angle of the scanner 3 in advance. With this configuration, from the calibration optical unit 8, the transmission light passing through the pinhole 83 for each scan of the scanner has a delay time corresponding to a predetermined length for distance calibration of the fiber 9 and is equal to the number of the pinhole transmission / reception optical units 2 Then, it is transmitted to the light receiving unit 5.
(Description of operation)
The operation will be described with reference to the configuration diagram of the embodiment shown in FIGS.
The laser pulse output from the laser 1 is partially reflected by the half mirror and transmitted to the light receiving unit 5, and the transmitted light is transmitted to the transmission / reception optical unit 2, beam-shaped, and transmitted to the scanner unit 3. The scanner unit 3 receives a biaxially driven angle command signal from the scanner driving unit 4 that operates by scanner control from the control unit 10, and has a scanner including a mirror that rotates around an axis. The beam from the optical unit 2 is scanned in two axes, and the three-dimensional information (angle data) of the scanner angle is detected and output to the control unit 10 via the scanner driving unit 4.

  As for the normal distance measuring function, the scanner unit 3 scans the beam of transmission light in the direction of detection of the target to be measured, receives the reflected light from the target as received light, and receives the light received through the transmission / reception optical unit 2 5 is transmitted. The light receiving unit 5 converts the received light into an electric signal in addition to the transmission light from the laser 1 and outputs it to the distance measuring counter unit 6. The ranging counter unit 6 counts the time between the transmission time of the transmission light pulse at the time of laser emission and the reception time of the reception light based on the electrical signals of the transmission light and the reception light to the target by counting the high frequency clock signal or the like. And the distance measurement count data is output to the control unit 10.

  Regarding the distance / angle calibration function, in the distance measuring operation, the scanner unit 3 scans the calibration optical unit 8 every time the transmission light beam is scanned as shown in FIG. The beam that scans the calibration optical unit 8 is condensed by the condenser lens 81, the condensed spot moves in the arrangement direction of the plurality of pinholes 83 of the shielding plate 82, and the condensed spot is located in the pinhole 83. At that time, the laser pulse that has passed through the pinhole 83 is incident from one end of the optical fiber 9 disposed on the lower side of the pinhole 83, and is emitted from the other end after a delay time corresponding to the distance calibration length. Then, the laser pulse is transmitted to the light receiving unit 5 through the transmission / reception optical unit 2, and this laser pulse is used for calibration of distance and angle.

  FIG. 3 is a diagram showing a detailed operation example of distance calibration and scanner angle calibration. By setting the diameter of the pinhole 83 that allows the laser beam to pass through the diameter of the condensing spot of the transmission light, when the condensing spot of the laser beam scans the pinhole 83, the optical fiber 9 in the light receiving unit 5 The resolution of the calibration accuracy can be improved by detecting and using the peak level (peak position). The relationship of d = f · θ holds among the focal length f of the condenser lens 81, the interval d of the pinhole 83, and the scan angle θ, and the interval between the peaks of the reception level of the light receiving unit 5 is measured. The scan angle θ can be calculated.

The distance and angle calibration operation of the present embodiment is as follows.
For distance calibration, a part of the transmission light from the scanner unit 3 is received by the calibration optical unit 8, and the transmission light transmitted through the pinhole 83 is transmitted to the transmission / reception optical unit 2 by the fiber 9 and received by the light receiving unit 5. Then, it is output to the distance measuring counter unit 6 as an electric signal. At this time, the time difference between the transmitted light and the received light measured by the distance measuring counter unit 6 corresponds to the delay time of the optical fiber 9, and the internal reference is obtained by using the optical fiber 9 having a fiber length calibrated in advance. Therefore, this information can be used as distance calibration information by the control unit 10.

  For angle calibration, the positions of the plurality of pinholes 83 of the shielding plate 82 are set in advance at positions corresponding to the reference angle of the scanner 3 and intervals corresponding to the reference relative angle, thereby passing through the plurality of pinholes 83. Depending on the peak position and the interval between the peaks of the laser pulse by the beam, it can be used for bias correction of the angle command signal and gain correction of the angle command signal, respectively.

  For the sake of simplicity, the angle calibration operation will be described as a single-axis scanner. As shown in FIG. 3, laser light transmitted through the pinhole 83 at a certain angle of the scanner is detected by the light receiving unit 5 through the optical fiber 9. The level of the received signal is detected by the level detection unit 7 and the peak level is transmitted to the control unit 10. The control unit 10 detects the correlation between the scanner angle signal from the scanner unit 3 and the peak level of the received light, calculates the angle from the peak level, and matches this angle with a known reference angle of the scanner. Determine whether or not. If the absolute value of the angle information measured by the beam that has passed through the two pinholes 83 is shifted by the same amount from the reference angle of the scanner, the control unit 10 generates a bias error of the reference angle angle. In addition, if the relative angle between the two pinholes measured by the beam passing through the two pinholes 83 does not match the angle command signal, the gain correction for the scanner angle command signal (gain correction) )I do.

(Other embodiments)
In the above embodiment, for an optical fiber that emits incident light after a predetermined time and serves as a reference for distance calibration in the apparatus, the incident position is set at the reference position for angle calibration, and the reference position for angle calibration A configuration example of a laser range finder has been described in which the optical fiber is also shared for obtaining the transmitted light of the apparatus, and the apparatus configuration can be made compact. However, as another embodiment of the present invention, for distance calibration, It is obvious that the optical fiber and the optical fiber for angle calibration can be individually provided.

  In addition, as described above, the distance and angle can be calibrated simultaneously with the apparatus configuration of the present embodiment, and the calibration optical unit 8 is outside the measurement range necessary for normal distance measurement (however, the scanning range of the scanner). It is possible to acquire calibration data at the same time as normal distance measurement.

Industrial application fields

  It can be installed on satellites, transport aircraft that perform rendezvous docking to space stations, and satellites for on-orbit services.

It is a figure which shows the structure of one Embodiment of the laser ranging apparatus of this invention. It is a figure which shows the structure of a scanner and the optical part for a calibration. It is a figure which shows the detailed operation example of distance calibration and angle calibration of a scanner.

Explanation of symbols

1 Laser (transmitter)
2 Transmission / reception optical unit 3 Scanner unit 4 Scanner drive unit 5 Light receiving unit 6 Ranging counter unit 7 Level detection unit 8 Calibration optical unit 9 Calibration optical fiber 10 Control unit 11 Power supply unit 81 Condensing lens 82 Shielding plate 83 Pinhole

Claims (10)

  A scanning laser distance measuring apparatus having a laser beam scanner, comprising: an optical fiber for distance calibration as an internal reference; and an optical fiber having an angle calibration reference position within the scanning range of the scanner as an incident position. A laser range finder characterized by the above.   2. The laser distance measuring apparatus according to claim 1, wherein an optical fiber having the reference position for angle calibration as an incident position is shared with the optical fiber for distance calibration.   3. The laser range finder according to claim 1, wherein the reference position for angle calibration is a position outside the scanning range of the target.   4. The laser range finder according to claim 1, wherein the reference position for angle calibration is a pinhole of a shielding plate scanned with a laser beam.   A condensing lens for the laser beam, and a shielding plate formed on the condensing surface of the condensing lens and formed with a plurality of pinholes having a beam divergence angle or less, and the pinhole is used as the reference for angle calibration. 4. The laser distance measuring device according to claim 1, wherein the laser distance measuring device is a position.   6. The laser range finder according to claim 5, wherein the pinhole is located in a scanning range of the scanner with a small change in light quantity within the scanning range of the scanner.   7. The laser ranging according to claim 5, wherein if the absolute value of the angle measured by the light passing through the plurality of pinholes is shifted by the same amount, the bias of the angle is corrected and the bias error is calibrated. apparatus.   8. The laser measurement according to claim 5, wherein gain correction of the angle command signal is performed if relative angles measured by light passing through a plurality of pinholes do not coincide with an angle command signal of the scanner. Distance device.   9. The laser range finder according to claim 1, wherein the laser range finder is a rendezvous docking laser range finder used when a transport aircraft is docked to an artificial satellite or a space station.   The marker of the satellite or space station mounted on the transport aircraft is laser-scanned by a two-dimensional scanner, the position of the marker is calculated from the distance information obtained from the round trip time of the pulse laser and the angle information of the scanner. 10. The laser distance measuring device according to claim 1, wherein guiding data is output.

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